Re: [squid-users] Persistent Connections to Parent Proxy

On 29/04/11 07:28, Jenny Lee wrote:
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>> Date: Fri, 29 Apr 2011 01:12:55 +1200
>> From: squid3_at_treenet.co.nz
>> To: squid-users_at_squid-cache.org
>> Subject: Re: [squid-users] Persistent Connections to Parent Proxy
>>
>> On 28/04/11 20:19, Mathias Fischer wrote:
>>> Hi,
>>>
>>> We use squid together with a content scanner connected as parent proxy
>>> (cache_peer parent) with none of them caching any content. When
>>> upgrading from squid 2.7 to 3.1, we observed an increased number of TCP
>>> connections between squid and its parent. I analysed the traffic between
>>> squid and the parent proxy (for both squid versions), and found (among
>>> some differences in HTTP version and (Proxy-)Connection header) that the
>>
>> Proxy-Connection: has never been a registered header suitable for
>> transmission. Squid-3 was mistakenly made to send it for a while instead
>> of just accept it. That bug has been fixed in recent releases.
>> Only Connection: shod be sent over the wire.
>>
>>> usage of persistent connections has changed. In squid 2.7, a persistent
>>> connection to the parent proxy is shared for multiple origin servers,
>>> while in squid 3.1, there is at least one connection per origin server.
>>> Obviously, this results in a much higher total number of connections.
>>
>> Hmm, I thought we corrected that the same way in both 3.1 and 2.7.
>> 3.0 and 2.6 certainly had that behaviour.
>>
>> Current 2.7 and 3.1 should have (peer_IP, domain_name) as the pconn key.
>> There can be multiple duplicates of course up to as many as needed to
>> handle peak load (moderated by how fast the peer closes them).
>>
>>>
>>> Is there a possibility to influence this behaviour? To me, it looks like
>>> this is related to the introduced Connection Pinning [1] feature.
>>
>> Pinning links one server FD per client connection, kind of an
>> independent and special type of persistence. It should not be showing
>> this behaviour, though yes it also will cause a multitude of server
>> connections.
>>
>>>
>>> As a workaround, I see the option to reduce the number of open
>>> persistent connections through pconn_timeout, but this will have an
>>> impact on other connections as well which could reduce performance.
>>
>> We have a re-structuring if the conn and pconn handling coming to 3.2
>> shortly (a few weeks) which removes the domain name from the pconn key.
>
> We have the same problem in 3.2.0.1 and 3.2.0.7
>
> Is this planned for 3.2.0.8?

Possibly, hopefully, depends on how much free time I have.

Amos

-- 
Please be using
   Current Stable Squid 2.7.STABLE9 or 3.1.12
   Beta testers wanted for 3.2.0.7 and 3.1.12.1